pkg/compiler/test/deferred/load_graph_segmentation2_test.dart

// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

// @dart = 2.7

// Test of the graph segmentation algorithm used by deferred loading
// to determine which elements can be deferred and which libraries
// much be included in the initial download (loaded eagerly).

import 'package:async_helper/async_helper.dart';
import 'package:compiler/src/compiler.dart';
import 'package:expect/expect.dart';
import '../helpers/memory_compiler.dart';

void main() {
  asyncTest(() async {
    CompilationResult result =
        await runCompiler(memorySourceFiles: MEMORY_SOURCE_FILES);
    Compiler compiler = result.compiler;
    var closedWorld = compiler.backendClosedWorldForTesting;
    var env = closedWorld.elementEnvironment;
    var outputUnitForMember = closedWorld.outputUnitData.outputUnitForMember;
    var mainOutputUnit = closedWorld.outputUnitData.mainOutputUnit;
    dynamic lib = env.lookupLibrary(Uri.parse("memory:lib.dart"));
    var f1 = env.lookupLibraryMember(lib, "f1");
    var f2 = env.lookupLibraryMember(lib, "f2");
    Expect.notEquals(mainOutputUnit, outputUnitForMember(f1));
    Expect.equals(mainOutputUnit, outputUnitForMember(f2));
  });
}

// The main library imports lib1 and lib2 deferred and use lib1.foo1 and
// lib2.foo2.  This should trigger separate outputunits for main, lib1 and lib2.
//
// Both lib1 and lib2 import lib3 directly and
// both use lib3.foo3.  Therefore a shared output unit for lib1 and lib2 should
// be created.
//
// lib1 and lib2 also import lib4 deferred, but lib1 uses lib4.bar1 and lib2
// uses lib4.bar2.  So two output units should be created for lib4, one for each
// import.
const Map<String, String> MEMORY_SOURCE_FILES = const {
  "main.dart": """
import "dart:async";

import 'lib.dart' deferred as lib show f1;
import 'lib.dart' show f2;

void main() {
  print(f2());
  lib.loadLibrary().then((_) {
    print(lib.f1());
  });
}
""",
  "lib.dart": """
int f1 () {
  return 1;
}

int f2 () {
  return 2;
}
""",
};